1. Technical Field
The present invention relates to an optical position detection device for optically detecting the position of a target object.
2. Related Art
As an optical position detection device for optically detecting the position of a target object, there is proposed a technology of emitting a detection light to the target object located on a first surface of a transmissive plate (light propagation medium) from a second surface thereof opposite to the first surface, and detecting the detection light, which is reflected by the target object and transmitted through the transmissive plate to the second surface thereof, with a light detector (see JP-T-2003-534554 (Document 1; the term “JP-T” as used herein means a published Japanese translation of a PCT patent application).
Here, the inventors study the optical position detection device for optically detecting the positions of target objects respectively located in two spaces such as the positions of a customer (a target object) located inside a store window and a customer (a target object) located outside the store window, or the positions of a game medium (a target object) located inside a cover glass of an amusement device and a player (a target object) located outside the cover glass thereof. However, in the technology described in Document 1, since the detection result in the light detector is obtained as a sum of intensities of the detection light beams reflected by the respective target objects located in the two spaces, there arises a problem that detection of the respective positions of the target objects located in the two spaces is not achievable.